The following patent documents 1 and 2 show conventional internal gear pumps.    Patent document 1: JP utility model publication 6-39109    Patent document 2: U.S. Pat. No. 6,244,843 B1
The internal gear pump disclosed in Patent document 1 includes trochoidal internal gear rotors generated based on the diameter A of a base circle, the diameter B of a rolling circle, the diameter C of a locus circle and eccentricity e.
The internal gear pump disclosed in Patent document 2 comprises an inner rotor including epicycloidal tooth tops and hypocycloidal tooth spaces, and an outer rotor including hypocycloidal tooth tops and epicycloidal tooth spaces.